Starter control for internal combustion engines



April 16, 1940. R. s. JOHNSON 2,197,726

STARTER CONTROL FOR INTERNAL COMBUSTION ENGINES I Filed Dec. 24, 19:8

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UUUUUUUUUUI 50 1 was 10 i Z1 6' Hill 22 31 VINVENTOR. l/U/b llleszs BY MS. John/5m Patented Apr. 16, 1940 PATENT OFFICE STARTER CONTROL FOR/INTERNAL COMBUSTION ENGINES Russell S. Johnson, Royal Oak, Mich., assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application December 24, 1938, Serial No. 247,563

Claims.

The present invention relates to a starter control for internal combustion engines and more particularly to a device for completely controlling 1 the cranking operation of a power plant in the 5 absence of an attendant.

Various forms of automatic starter controls are available for instituting the cranking operation of an internal combustion engine and for rendering the starting mechanism inoperative rel0 sponsive to self-operation of the engine or to failure of the engine to start after a predetermined time of cranking. It is well known, however, that it is usually better for the starting battery, and more efliclent as respects electrical energy consumed, to not crank continuously over an extended period in case the engine fails to start promptly but to crank repeatedly after short intervals of rest to allow the battery to recuperate somewhat and to permit the more volatile factions of the fuel to evaporate and form a combustible mixture.

It is an object of the present invention to provide a novel starter control for internal combustion engines which is arranged to crank the engine repeatedly with intervals of rest between the cranking periods.

It is another object to provide such a device which is arranged to continue the attempts to start the engine for a predetermined time, and ii the engine fails to become self-operative after a predetermined total cranking time, the starting operation is terminated and the ignition and control circuits maintained open.

It is another object to provide such a device in which the relation of the cranking periods and rest intervals may be readily varied, and the total cranking time before termination of the starting operation may be easily adjusted.

It is another object to provide such a device which is reliable in operation and simple and economical in construction. i

Further objects and advantages will be apparent from-the following description taken in connection with the accompanying drawing which represents semi-diagrammatically one preferred form of the invention.

In the drawing, a starting circuit for cranking an internal combustion engine, not illustrated, is

provided comprising a battery I grounded at 2 and connected by a lead 3 to a magnetic starting switch 4 of an automatic starter controlling device indicated generally by numeral Ill. Switch 4' is connected by a lead I, a single turn electromagnet 3 and lead I to a starting motor 8M which is grounded at 8 to complete the starting circuit.

A control circuit for the magnetic starting switch 4 is provided which branches ofi from the battery lead 3 and includes manual switch 9, leads I l and I2, coil 13 of the magnetic starting switch, lead l4 and normally closed contacts l5 and IS, the latter of which is mounted on a flexible metal reed l6, grounded as indicated at ll. A coil l8 connected by lead l9 to the starting circuit lead 5 and grounded at 2| is provided for actuating a plunger 20 to open contacts l5, Hi. When the engine becomes self-operative, the load on the cranking circuit is reduced, and the coil I8 is thus caused to overcome the series coil 6 and open contacts l5, l6 and thereby stop the cranking operation. A coil 22 also grounded at 2| and connected by a lead 23 to an engine-driven generator G is provided for maintaining contacts l5, l6 open during self-operation of the engine.

According to the present invention, a thermostatic controlling device indicated generally by numeral 24 is interposed between leads H and I2 of the control circuit and is so arranged that when the manual switch 9 is closed, cranking will take place intermittently for a predetermined time, after which if the engine refuses to start, the control circuit is maintained open. As here shown, the thermostatic device comprises a casing 25 having a strip of thermostatic material 26 mounted at one end on an insulated binding post 21 to which lead II is attached, and carrying at its other end a contact 28 which is normally in engagement with a fixed contact 29. Contact 29 is carried by bracket 3| mounted in the-opposite end of the casing 25 as by means of an insulated bolt 32. Bracket 3| is maintained by bolt 32 in electrical contact with a'spring arm 33, the free end of which carries a contact 34 arranged to engage a contact 35 mounted on an insulated binding post 36 to which lead l2 isattached.

A plunger 31 is slidably mounted in the casing 25 and is provided with a cylindrical cam member 38 of insulating material fixed thereon. Cam 38 is arranged to engage a projecting portion 33 of spring arm 33 and thereby holdcontact 34 in engagement with contact 35 when the plunger is in the normal position as illustrated. A spring 4| on-plunger 3'l urges the plunger to a position where a groove 42 in the cam member 38 will register with the projection 39 of the spring arm 33, thereby permitting the spring arm to expand and move contact 34 away from contact 35, This action is normally prevented, however, by a thermostatic latch 43 mounted at one end in the casing 25 as indicated at 44 and engaging at its free end against a shoulder 45 of the plunger so as to maintain the plunger in the position illustrated.

Means for heating the thermostatic elements 26 and 43 during the cranking operation are provided in the form of heater coils 45 and 41 respectively, coil 46 being connected by a lead 48 to the lead 5 of the starting circuit, and by a lead 49 to the coil 41 which is grounded at 5!.

The thermostat comprising the element 26 and the heater coil 46 is so designed and proportioned that the contacts 28, 29 will be opened after a suitable predetermined period of continuous cranking'such as, for instance, ten or fifteen seconds. Means for readily adjusting this thermostat to vary the cranking periods is provided in the form of an adjusting screw 50 threaded in the casing 25 and engaging a block of insulating material 50 fixed in any suitable way to the thermostatic strip 26. The thermostat comprising the element 43 and heater coil 41 is designed to be considerably slower in its action so that the thermostatic latch will not free the plunger 31 until after several cranking periods have elapsed. Thus, the thermostatic latch might be arranged to require forty-five seconds or more to operate. In order to integrate the effect of the cranking periods on the thermostatic latch so as to cause its eventual operation, thermal insulating means of any suitable type indicated at 52 is provided for retarding the escape of heat from the thermostatic latch. Means for adjusting the latch 43 to control the total cranking time before termination of the starting operation is provided in the form of an adjusting screw 53 therefor threaded in the casing 25.

In operation, starting with the parts in the positions illustrated, closure of the switch 9 completes the control circuit whereby the coil I3 is energized to close the magnetic switch 4. The starting motor is thereby energized to crank the engine. If the engine starts, contacts l5, IE will be opened by the coil 18, overcoming the effect of the single turn coil 6 on the relay plunger 20, and said contacts are thereafter maintained open by the coil 22 energized from the engine-driven generator G.

Upon closure of the starting switch 4, however, the heater circuit through the heater coils 46 and 4'! is completed, and if the engine fails to start after a predetermined short time of cranking, thermostat 26 acts to open contacts 28, 29 which breaks the control circuit, and cranking is interrupted by the opening of magnetic switch 4. The heating circuit is thus broken, and thermostat 26 cools ofi', whereby after a predetermined delay, contacts 28, 29 close, thus reclosing the control circuit and causing cranking to be resumed.

If the engine still fails to operate, cranking thereof takes place intermittently under the control of thermostat 26. However, during each pe riod of cranking, the thermostatic latch 43 receives heat from the coil 41, which heat is largely confined by the insulation 52 so that the latch 43 becomes progressively hotter. After a predetermined number of attempts to start have been made, the latch will be operated to release the plunger 3'1, whereupon contacts 34, 35 are opened and remain open until reclosed by an attendant after he has ascertained and corrected the inoperative condition of the engine.

It will be understood that the switch 9 may be operated by remote control or by any form of automatic means responsive to suitable stimulus or demand for power from the power plant to be started. It will be further understood that any suitable form of alarm or indicator may be actuated by the plunger 31 in order to indicate at a distance the failure of the engine to become selfoperative.

Although but one form of the invention has been shown and described in detail, it will be understood that other embodiments are possible and various changes may be made in the design and arrangements of the parts without departing from the spirit of the invention as defined in the claims appended hereto.

What is claimed is:

1. In an engine starter control, a starting circuit including a battery, a starting motor and a magnetic starting switch, and a control circuit for the starting switch including two pairs of contacts in series, and a thermostatic device energized during the starting operation for opening each pair of contacts, one of said thermostatic devices being comparatively quick-acting, and the other comparatively slow-acting.

2. In an engine starter control, a starting circuit including a battery, a starting motor and a magnetic starting switch, and a control circuit for the starting switch including two pairs of contacts in series, quick-acting and slow-acting thermostatic devices for opening said pairs of contacts respectively, and means for retarding the escape of heat from the slow-acting thermostatic device.

3. In an automatic starter control for internal combustion engines, a starting circuit including a starting motor, a battery and a magnetic starting switch, a control circuit for the starting switch including two pairs of normally closed contacts in series, a quick-acting thermostatic means energized by closure of the magnetic starting switch for opening one pair of contacts, and a slow-acting thermostatic means similarly energized for opening the second set of contacts, the opening means for the second pair of contacts being effective to hold said contacts open irrespective of cooling oif of the thermostat.

4. In an automatic starter control for internal combustion engines, a magnetic starting switch, a control circuit, closure of which causes closure of the starting switch, said control circuit comprising two pairs of normally closed contacts in series, quick-acting thermostatic means energized by closure of the starting switch for opening one pair of contacts, said contacts being arranged to reclose upon cooling of the thermostat, and slow-acting thermostatic means energized by closure of the starting switch to open and maintain open the second pair of contacts, said slow-acting thermostatic means being thermally insulated to retard the cooling thereof.

5. In an automatic starter control, thermostatic means to periodically interrupt the cranking operation for predetermined time intervals, and thermostatic means for terminating the cranking operation after a predetermined total cranking time, substantially as shown and described.

RUSSELL S. J OHNSON. 

